# The Boudouard–Bell reaction analysis under high pressure conditions

Journal of Thermal Analysis and Calorimetry

, Volume 110, Issue 1, pp 93–102

First Online: 18 March 2012

Abstract

A new method for the measurement of solid fuel reactivity towards carbon dioxide has been developed. This new method takes into account high-pressure and temperature effects. Three devolatilized carbonaceous materials have been used in experiments: chars derived from lignite, bituminous coal and blast furnace coke. Processes were carried out at temperatures of 800, 850 and 900 °C and pressures of 1.52, 2.5 and 3.4 MPa. Analysis of the product gas composition was carried out with the maximum degree of conversion of CO2 αm proposed as a representative reactivity parameter. Arrhenius and Eyring relationships have been analyzed, and values of the activation energy and activation volume have been calculated.

KeywordsBoudouard–Bell reaction CO2 Gasification reactivity Kinetics Temperature Pressure List of symbolsαConversion degree of CO2, \ 0 < \alpha < 1 \

αmMaximum obtained conversion degree of CO2 during process, \ 0 < \alpha {\text{m}} \le 1 \

αsConversion degree of solid phase of fuel, \ 0 \le \alpha {\text{s}} \le 1 \

A, A1, A2Pre-exponential factor in Arrhenius equation, s or dimensionless

b1, b2, b3Constants in L–H Eq. 8 related with kinetic constants

B, B1, B2Constants in Eqs. 12–13, 15, dimensionless

C0Constant in Eqs. 24, 25, Ks

C, C1, C2Constants

CO2, COMolar fractions of CO2 and CO, respectively, 0 ≤ CO2 ≤ 1, 0 ≤ CO ≤ 1,

COmMaximum obtained molar fraction of CO, 0 < CO ≤ 1

DFEDistance from thermodynamic equilibrium, dimensionless

EActivation energy, J mol

kRate coefficient, s, indexed constants corresponds with adequate equations

kgRate coefficient acc. to 23

KEquilibrium constant, calculated acc. to Eq. 34, dimensionless

KαApproximated equilibrium constant, defined with 32, dimensionless

mMass of sample, g

m0Initial mass of sample, g

\ \dot{m} \Mass flow of CO2 in ambient temperature, g s,

ηThermodynamic yield of process-reaction, 0 ≤ η ≤ 1

ΔνSum of stoichiometric coefficients of gaseous reactants

PPressure of CO2, MPa

PStandard pressure ~0.1 MPa

R8.314 J molK, gas constant

\ \dot{R} \Solid phase conversion rate, defined acc. to 5, s

rDetermination coefficient, 0 ≤ r ≤ 1

T0Ambient temperature, K

TReaction-process temperature, K

VVolume of particular reactant, cm mol

\ \dot{V} \Volumetric flow of CO2 in ambient temperature, cm s,

ΔVVolume of activation, cm mol

τTime, s

τmTime to obtain maximum conversion of CO2, s,

τ0Initial time in Eq. 12, h

τzEquivalent time, s

Subscriptss, gRepresents solid and gaseous phase, respectively

eqEquilibrium state

Author: Andrzej Mianowski - Zbigniew Robak - Martyna Tomaszewicz - Sławomir Stelmach